JP2007150970A - Digital content video recorder and tamper resistant module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To impose copy limitations by recording media where digital contents are recorded and to prevent digital contents from illegally being used. <P>SOLUTION: A deciphering circuit 21 deciphers digital contents processed by first ciphering, a deciphering circuit 22 performs second ciphering for the deciphered digital contents, and an HDD 15 stores the digital contents processed by the second ciphering. A content management section 23 limits uses of the digital contents by kinds of recording media 18-1 to 18-n, based on content management information having pieces of information by the recording media 18-1 to 18-n where stored digital contents are recorded. The deciphering circuit 21, ciphering circuit 22, and content management section 23 are incorporated in a tamper resistant module 20 and then protected against illegal access. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a digital content recording apparatus and a tamper resistant module, and more particularly to a digital content recording apparatus and a tamper resistant module for recording digital content with copy restrictions.

  Recently, digital broadcasting has begun to spread. Unlike conventional analog content, digital content does not degrade image quality, regardless of how many times it is copied. In addition, there is a possibility of being distributed over the Internet, which is very troublesome for the right holder.

FIG. 5 is a diagram showing a configuration of an example of a conventional digital television broadcast receiver.
Here, a digital television broadcast receiver (hereinafter referred to as a digital broadcast receiver) 800 having a copy control function for copying digital content to a DVD (Digital Versatile Disc) is shown.

  The digital broadcast receiver 800 includes a tuner 801 that receives a digital broadcast, a decryption circuit 802 that decrypts encrypted digital content, an encryption circuit 803 that encrypts the decrypted digital content again, and an encrypted digital content. An HDD (Hard Disk Drive) 804 for storing contents is included. Furthermore, as a configuration for reproducing or copying the encrypted content stored in the HDD 804 to a DVD, a decryption circuit 805, an MPEG decompression circuit 806 for decoding digital content in the MPEG (Motion Picture Expert Group) format, and HD, for example, Format conversion circuit 807 for down-converting (High-Definition) format data to DVD format, and DVD encryption for performing DVD standard encryption (eg, CPRM (Content Protection for Recordable Media)) to prevent illegal copying A circuit 808 is included.

  These are controlled by the processor 809 via the bus 810. Also, the bus 810 includes a nonvolatile memory (for example, a flash memory) 811 in which various programs such as a receiver control program and a DVD recording control program are stored, and a DRAM (Dynamic Random Access Memory) 812 that is a work area of the processor 809. Is connected. Further, an IC (Integrated Circuit) card (for example, a B-CAS (BS-Conditional Access Systems) card) 813 in which a decryption key for decrypting the received digital content is recorded is connected to the bus 810 via an interface circuit (not shown). It is connected.

Hereinafter, the operation of the conventional digital broadcast receiver 800 will be described.
First, a digital broadcast stream that is encrypted and MPEG-compressed is input to the tuner 801 as a radio wave. When the tuner 801 receives this, the decryption circuit 802 obtains the decryption key contained in the IC card 813 via the bus 810 and decrypts it. Further, the encryption circuit 803 re-encrypts the decrypted digital content and records it in the HDD 804. This is to prevent the HDD 804 from being taken out illegally and being played back illegally by other devices.

  When viewing the encrypted content stored in the HDD 804, the encrypted content is decrypted by the decryption circuit 805, decoded by the MPEG decompression circuit 806, and then output to a display device (not shown).

  In addition, when recording on a DVD, after decrypting and decoding in the same manner, the digital content is converted into a DVD format by a format conversion circuit 807, and further encrypted by a DVD encryption circuit 808 to prevent illegal copying. Is recorded on a DVD.

  At this time, in order to prevent unlimited DVD copying, the conventional digital broadcast receiver 800 takes the following measures. That is, the recording of the digital content recorded on the DVD is recorded in the non-volatile memory 811. For example, once recorded on the DVD, it is not recorded on the DVD thereafter. Therefore, content management information such as a content ID of encrypted content recorded in the HDD 804, an encrypted content key, and a flag indicating whether or not recording has been performed on the DVD exists in the nonvolatile memory 811. The processor 809 that controls the entire digital broadcast receiver 800 confirms the content management information stored in the nonvolatile memory 811 and, among encrypted content stored in the HDD 804, has not been recorded on, for example, a DVD in the past. The DVD recording control is executed only on the object.

  The copy control processing in the conventional digital broadcast receiver 800 has been described above. The inside of the digital broadcast receiver 800 is regarded as a safe area (hereinafter referred to as a secure area) that cannot be hacked by at least a general hacker.

By the way, in recent years, personal computers (hereinafter referred to as PCs) capable of viewing or recording digital broadcasts have appeared.
In a PC capable of viewing or recording a digital broadcast, for example, a decryption circuit 802, an encryption circuit 803, a decryption circuit 805, an MPEG decompression circuit 806, and a format conversion circuit as shown in FIG. 807, DVD encryption circuit 808 and the like are preferably executed by software.

  Most PC architectures (including software architecture, PC data memory area access method, HDD memory access method, PC program memory area access method, etc.) are known. Because it is publicly known, third-party software houses around the world can develop a variety of applications, which is helping to popularize PCs. However, what is known on the other hand is that hackers and the like can look into the software area and tamper with it.

  In order to prevent such unauthorized use of digital content, there has been a technology for ensuring safety by verifying a tamper-resistant module for processing software that may be hacked (see, for example, Patent Document 1). ). The tamper resistant module is a hardware module having a structure in which information stored in an internal LSI (Large Scale Integrated circuit) or the like cannot be referred to from the outside. Moreover, the software protected by the LSI is a tamper resistant module in a broad sense that cannot be illegally used.

By the way, in recent years, the types of recording media for recording digital contents have increased. In addition to DVDs, there are various types such as SD (Secure Digital) memory cards used for mobile phones and Blu-Ray Disc (registered trademark). is there.
JP 2003-198527 A

  However, the conventional digital content recording apparatus has a problem of lack of flexibility because copy restriction is performed regardless of the type of recording medium to be recorded. For example, in the case of digital content of a high-definition image that can be copied once, there is a problem that even if the digital content is stored by being down-converted and recorded on a DVD or SD memory card, the digital content can no longer be viewed as a high-definition image. It was.

  The present invention has been made in view of the above points, and provides a digital content recording apparatus capable of restricting copying for each recording medium for recording digital content and preventing illegal use of digital content. Objective.

  Another object of the present invention is to provide a tamper resistant module capable of restricting copying for each recording medium for recording digital content and preventing unauthorized use of the digital content.

  In the present invention, in order to solve the above problem, in the digital content recording apparatus for recording digital content with copy restrictions, as shown in FIG. 1, a decrypting unit (1) that decrypts the digital content subjected to the first encryption. A decryption circuit 21), an encryption unit (encryption circuit 22) for performing second encryption on the decrypted digital content, and an encrypted content storage for storing the digital content subjected to the second encryption Records the use of the digital content based on the content management information having information for each type of the recording medium 18-1, 18-2,. Content management unit 23 that restricts each type of medium 18-1 to 18-n, and includes a decryption unit (decryption circuit 21) and an encryption unit (encryption circuit 22). And the content management unit 23 the digital content recording apparatus 10, characterized in that incorporated in the tamper resistant module 20 is provided.

  According to the above configuration, the decryption circuit 21 decrypts the first encrypted digital content, the encryption circuit 22 performs the second encryption on the decrypted digital content, and the HDD 15 2 stores the digital content that has been encrypted. The content management unit 23 determines the use of the digital content based on the content management information having information for each type of the recording media 18-1 to 18-n that records the stored digital content. Since the restriction is made for each type of -n, the copy restriction is made for each kind of the recording media 18-1 to 18-n. In addition, by incorporating the decryption circuit 21, the encryption circuit 22, and the content management unit 23 in the tamper resistant module 20, the decryption circuit 21, the encryption circuit 22, and the content management unit 23 are protected from unauthorized access from the outside.

  In the present invention, the decryption unit decrypts the first encrypted digital content, the encryption unit performs the second encryption on the decrypted digital content, and the encrypted content storage unit The content management unit stores the use of the digital content based on the content management information having information for each type of the recording medium on which the stored digital content is recorded. Therefore, copy restriction can be executed for each type of recording medium.

  Further, by incorporating the decryption unit, encryption unit, and content management unit in the tamper-resistant module, unauthorized access from outside to these can be prevented, and unauthorized use of digital content can be prevented.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram illustrating a configuration of a digital content recording apparatus according to the first embodiment.
Here, a PC is assumed as the digital content recording apparatus 10, but the present invention is not particularly limited thereto.

  The digital content recording apparatus 10 stores a tuner 11 that receives a digital broadcast, an IC card 12 (for example, a B-CAS card) that records a decryption key for decrypting the received digital content, content management information that will be described later, and the like. It has a non-volatile memory 13 (for example, a flash memory). In addition, the HDD 14, the DRAM 16, the output circuit 17, the interface unit 18, the processor 19, and the tamper resistant module 20 are connected to the bus 14.

The HDD 15 stores encrypted digital content, commercial data, and the like.
The DRAM 16 is a work area of the processor 19. For example, various programs stored in the HDD 15 are expanded to perform digital content recording processing and reproduction processing.

A display device 17a and a speaker 17b are connected to the output circuit 17 and output image data and audio data of the reproduced digital content.
Various recording media 18-1, 18-2,..., 18-n are connected to the interface unit 18, and digital content data sent via the bus 14 is recorded on the recording media 18-1 to 18-n. To record.

  As the recording media 18-1 to 18-n, there are, for example, an SD memory card used for a mobile phone, a Blu-Ray Disc, and the like in addition to a DVD. Further, for example, a computer capable of recording digital content via a LAN (Local Area Network) based on a content protection standard such as DCTP-IP (Digital Transmission Content Protection over Internet Protocol) also includes a recording medium in this specification. Consider one of 18-1 to 18-n.

The processor 19 is a CPU (Central Processing Unit), for example, and controls each unit of the digital content recording apparatus 10 via the bus 14.
The tamper resistant module 20 which is a characteristic part of the digital content recording apparatus 10 of the present embodiment is configured by an LSI having a structure in which information stored therein cannot be referred to from the outside. The tamper resistant module 20 includes a decryption circuit 21, an encryption circuit 22, a content management unit 23, and a software processing protection unit 24. Although not shown in FIG. 1, the tamper-resistant module 20 includes, for example, an MPU (Micro Processing Unit), which controls the decryption circuit 21 and the encryption circuit 22, and controls the content management unit 23 and software. The function of the processing protection unit 24 is realized.

  The decryption circuit 21 decrypts the encrypted digital content input from the tuner 11. The decryption key at this time is acquired from the IC card 12 via an IC card interface (not shown). The digital content stored in the HDD 15 is decrypted when the digital content is reproduced or recorded on the recording media 18-1 to 18-n. Note that the decryption key is periodically updated. Each time it is updated, a new decryption key is obtained from the IC card 12.

  The encryption circuit 22 re-encrypts the digital content decrypted by the decryption circuit 21 based on the encryption key information randomly generated by the MPU in the tamper resistant module 20 and outputs it to the HDD 15 via the bus 14. .

  The content management unit 23 restricts the use of the digital content for each type of the recording media 18-1 to 18-n and each digital content based on the content management information stored in the nonvolatile memory 13 that is a secure area.

The content management information includes information for each type of recording media 18-1 to 18-n for recording digital content. Here, an example of content management information is shown.
FIG. 2 is a diagram illustrating a first example of content management information.

  In the content management information, in addition to the content ID and the encryption key information used in the encryption circuit 22, information on the number of times that recording is possible for each type of the recording media 18-1 to 18-n (actual value, limit value) Is included. In this figure, for example, the digital content with the content ID “0001” can be copied once to the DVD and can be copied three times to the SD memory card. This indicates that the data has already been copied once to the DVD and SD memory cards. If the limit value is known, no description is necessary.

  In addition, the number of copies for each digital content (number of times the digital content can be recorded), the number of copy generations, the number of viewing times, the viewing time limit, and whether or not to allow trick play (CM (commercial) cuts are permitted in the content management information. Or not), CM viewing management information (such as forced viewing of CM), and the like. Such content management information can be obtained through various routes such as via the Internet or broadcast waves.

  Each time digital content is recorded on the recording media 18-1 to 18-n, the content management unit 23 can record for each type of the recording media 18-1 to 18-n in the content management information as shown in FIG. Update the number of times of information and the number of copies of digital content.

  Returning to FIG. 1, the software processing protection unit 24 built in the tamper resistant module 20 protects the software processing developed on the DRAM 16. This function is particularly important when digital content recording processing is performed on a PC. This is because only the most secure circuits such as the decryption circuit 21 and the encryption circuit 22 can be built in the tamper resistant module 20 and other processes can be made into software. As a result, hacking can be prevented and costs can be reduced.

  The protected software is also a tamper-resistant module in a broad sense, and it is conceivable that a part of the content management information is processed with the protected software. For example, an implementation in which the tamper resistant module 20 confirms the content management information, the protected software receives the information, and requests DVD recording, content viewing, and content output to the tamper resistant module 20 is also conceivable. If the software is appropriately protected tamper-resistant module, such an implementation is no problem.

  Specific software protection is disclosed in, for example, Japanese Patent Application Laid-Open No. 2003-198527 and Japanese Patent Application Laid-Open No. 2004-129227, and detailed description thereof is omitted. However, hacking detection of software operating on the DRAM 16 is detected in real time. If hacking is detected, the software operation is invalidated.

The operation of the digital content recording apparatus 10 according to the first embodiment will be described below.
When receiving the digital content, the tuner 11 inputs the digital content to the tamper resistant module 20. At this time, the digital content is input after being MPEG-compressed and further encrypted.

  The decryption circuit 21 of the tamper resistant module 20 acquires a decryption key corresponding to the digital content input from the IC card 12 and decrypts it using the decryption key. Thereafter, the encryption circuit 22 re-encrypts the digital content decrypted by the decryption circuit 21 based on encryption key information randomly generated in the tamper resistant module 20 (such encryption is generally performed). This is called local encryption.) Then, the encrypted content is output to the HDD 15 via the bus 14. The encrypted content stored in the bus 14 and the HDD 15 is protected by the effect of local encryption.

  When using the encrypted content stored in the HDD 15, the tamper resistant module 20 reads the encrypted content via the bus 14. Then, the decryption circuit 21 acquires the encryption key information of the content management information as shown in FIG. 2, and decrypts the encrypted content. The content management unit 23 refers to the content management information and re-encrypts the digital content if the recordable number of times for each type of the recording media 18-1 to 18-n and other conditions are satisfied. The data is output and passed to a software process executed on the DRAM 16.

  For example, when executing software for recording on a DVD, recording processing protected by the software processing protection unit 24 is performed on the DRAM 16 under the control of the processor 19 for the encrypted digital content. In the DVD recording process, first, the encrypted digital content is decrypted and subjected to MPEG decompression. For example, when the digital content received by the tuner 11 is a high-definition image, the DVD can only handle a standard level image, so down-conversion is performed. Further, DVD standard encryption (for example, CPRM) is performed to prevent unauthorized copying, and the data is written on the DVD. At this time, the content management unit 23 updates the content management information to increase the number of recorded digital content DVDs (the actual value in FIG. 2) by one. If the actual value matches the limit value, the subsequent digital content cannot be recorded on the DVD.

  When recording on other types of recording media 18-1 to 18-n, it is almost the same as described above, and encryption corresponding to each type is performed and recording is performed on each recording medium 18-1 to 18-n. To do. Thereafter, the content management unit 23 updates information on the number of recordable times in the types of the recorded recording media 18-1 to 18-n.

  In addition, when digital contents are reproduced by the display device 17 a and the speaker 17 b via the output circuit 17, the MPEG decompressed data is output from the output circuit 17. Then, the content management unit 23 updates information such as the number of viewing times of the content management information.

As described above, according to the digital content recording apparatus 10 of the first embodiment, it is possible to restrict copying for each type of the recording media 18-1 to 18-n.
Further, by incorporating in the tamper resistant module 20 a circuit that requires the most safety, such as the decryption circuit 21 and the encryption circuit 22, unauthorized use of digital content due to hacking can be prevented.

  By the way, in the above, when the number of recordable times for each type of the recording media 18-1 to 18-n is used as the information for each type of the recording media 18-1 to 18-n included in the content management information. However, the following information may be used.

FIG. 3 is a diagram illustrating a second example of content management information.
In addition to the content ID, the content management information shown here includes encryption key information (DVD key, SD memory card key (SD key), Blu-Ray, for each type of the recording medium 18-1 to 18-n. Other conditions for each digital content such as a Disc key (BD key)) and the number of viewing times described above are included. The encryption key information for each type of the recording media 18-1 to 18-n is managed by the encryption circuit 22 when it is encrypted.

  That is, the encryption circuit 22 is an encryption process performed when digital content is stored in the HDD 15, and dedicated encryption key information (DVD key, SD key) for each type of the recording media 18-1 to 18-n. Encryption using a BD key). In this case, the HDD 15 stores digital content encrypted with a DVD key, an SD key, a BD key, or the like.

  The content management unit 23 performs copy restriction using content management information as shown in FIG. Specifically, when digital content is recorded on a certain type of recording medium 18-1 to 18-n, the encryption key information used for encryption is deleted so that it cannot be decrypted.

  For example, when digital content with the content ID “0001” as shown in FIG. 3 is recorded on the SD memory card, the tamper resistant module 20 acquires the digital content encrypted with the SD key from the HDD 15 and uses the decryption circuit 21. Decrypt. The digital content is re-encrypted by the encryption circuit 22 and then transferred to the software side that performs the recording process. When digital content is recorded on the SD memory card, the content management unit 23 deletes the SD key of the recorded digital content so that the digital content encrypted with the SD key cannot be decrypted. The digital content encrypted with the SD key stored in the HDD 15 may be deleted. Further, instead of deleting the SD key by recording on the SD memory card once, the SD key may be deleted when recording is performed a plurality of times.

  In the above description, the content management information is recorded in the nonvolatile memory 13. However, when the content management information is enlarged and exceeds the memory capacity of the nonvolatile memory 13, it is encrypted and recorded in the HDD 15. It may be. In this case, the content management information in the HDD 15 is copied without limitation, and there is a possibility that the latest content management information and the old content management information cannot be distinguished. Therefore, every time the content management information is updated, information (hash value) indicating that the content management information is the latest is recorded in the secure area (for example, the nonvolatile memory 13). At the time of recording on the recording media 18-1 to 18-n, the content management unit 23 compares the content management information in the HDD 15 with the hash value, so that the read content management information is the latest. Can be checked.

Next, a digital content recording apparatus according to the second embodiment will be described.
The digital content recording apparatus 10a of the second embodiment is suitable for a digital broadcast receiver, for example.

FIG. 4 is a diagram illustrating a configuration of a digital content recording apparatus according to the second embodiment.
The same components as those of the digital content recording apparatus 10 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In the digital content recording apparatus 10 according to the first embodiment, the software processing protection unit 24 is built in the tamper resistant module 20 to protect software processing such as recording processing executed on the DRAM 16. On the other hand, the digital content recording apparatus 10a according to the second embodiment performs recording processing or the like not with software but with the processing circuits 25-1, 25-2,..., 25-m. The processing circuits 25-1 to 25-m are built in a tamper resistant module 20a made of a one-chip LSI together with a decryption circuit 21a, an encryption circuit 22a, and a content management unit 23a.

  The processing circuits 25-1 to 25-m include an MPEG2 or H264 decompression processing circuit, a down-converter circuit for recording on a DVD or SD memory card, a DVD or SD memory card, a BD encryption circuit, a wireless LAN, There is an encryption circuit according to the DTCP-IP standard for encrypting and transmitting digital content when recording digital content in a computer connected to a LAN.

The operation of the digital content recording apparatus 10a according to the second embodiment will be described below.
The process of encrypting the received digital content and storing it in the HDD 15 is the same as that of the digital content recording apparatus 10 of the first embodiment.

  When recording the digital content in the recording media 18-1 to 18-n, the tamper resistant module 20 a acquires the encrypted digital content from the HDD 15 via the bus 14. Then, the digital content is decrypted by the decryption circuit 21a. The content management unit 23a refers to content management information (obtained from the nonvolatile memory 13 or the HDD 15) and determines whether various conditions are satisfied. As described above, the various conditions include the number of times of recording (see FIG. 2) for each type of the recording media 18-1 to 18-n, and encryption corresponding to the type of the recording media 18-1 to 18-n. The presence / absence of activation key information (see FIG. 3), the number of copies for each digital content, and the like. When these conditions are satisfied, the content management unit 23a selects the processing circuits 25-1 to 25-m according to the types of the recording media 18-1 to 18-n as recording destinations and performs various recording processes. Let it run. Further, the content management unit 23a updates the content management information.

  When playing back the stored digital content, the tamper resistant module 20 a acquires the digital content to be played back from the HDD 15 via the bus 14. Then, the digital content encrypted by the decryption circuit 21a is decrypted. The content management unit 23a refers to the content management information to determine whether the number of viewing times or the viewing time limit of the digital content to be reproduced satisfies the conditions. When these conditions are satisfied, the content management unit 23a selects the processing circuits 25-1 to 25-m that perform processing (decoding processing of MPEG2 or H264) for reproducing the decrypted digital content, and performs the reproduction processing. Let it be done. Thereafter, the content management unit 23a updates content management information such as the number of viewing times.

  According to the digital content recording apparatus 10a of the second embodiment, the processing circuits 25-1 to 25-m for performing the recording process corresponding to the various recording media 18-1 to 18-n are provided in the tamper resistant module 20a. By incorporating it, it is possible to more strongly prevent valuable digital content from being illegally used due to hacking.

  Such a tamper resistant module 20a may be configured by a multi-chip LSI. In this case, the respective LSIs mutually authenticate each other, thereby ensuring security that makes signal theft difficult.

  In the digital content recording device 10, 10a according to the first or second embodiment, the tamper-resistant module 20, 20a has a public key encryption circuit built therein, and performs mutual authentication with the public key management center via the network. Thus, the validity of the tamper resistant modules 20 and 20a may be authenticated.

(Supplementary note 1) In a digital content recording apparatus for recording digital content with copy restrictions,
A decryption unit for decrypting the digital content subjected to the first encryption;
An encryption unit for performing second encryption on the decrypted digital content;
An encrypted content storage unit for storing the digital content subjected to the second encryption;
A content management unit that restricts use of the digital content for each type of the recording medium based on content management information having information for each type of the recording medium for recording the stored digital content;
Have
A digital content recording apparatus, wherein the decryption unit, the encryption unit, and the content management unit are built in a tamper resistant module.

(Supplementary Note 2) The content management information includes information on the number of recordable times for each type of the recording medium,
The digital content recording apparatus according to appendix 1, wherein the content management unit updates the information of the recordable number of times each time the digital content is recorded on the recording medium.

(Appendix 3) The encryption unit performs the second encryption with different encryption key information for each type of the recording medium,
The content management information includes the encryption key information that is different for each type of the recording medium,
The digital content recording apparatus according to appendix 1, wherein the content management unit deletes the encryption key information corresponding to the type of the recorded recording medium.

  (Supplementary note 4) The digital content according to supplementary note 1, wherein a software processing protection unit that protects recording processing to the recording medium developed on an externally accessible storage area is further incorporated in the tamper resistant module. Recording device.

  (Supplementary note 5) The digital content recording apparatus according to supplementary note 1, wherein a plurality of processing circuits that perform recording processing according to the type of the recording medium are further incorporated in the tamper resistant module.

(Supplementary note 6) The digital content recording apparatus according to supplementary note 5, wherein the tamper resistant module is a one-chip semiconductor integrated circuit.
(Supplementary note 7) The digital content recording apparatus according to supplementary note 5, wherein the tamper resistant module is composed of a plurality of chips of semiconductor integrated circuits, and the semiconductor integrated circuits mutually authenticate each other.

(Supplementary Note 8) The content management information includes information on the number of recordable times for each digital content,
The digital content recording apparatus according to appendix 1, wherein the content management unit updates the recordable number of times each time the digital content is recorded.

  (Supplementary note 9) The digital content recording apparatus according to supplementary note 1, wherein the content management information includes any one of a copy count, a copy generation count, a viewing count, a viewing deadline, trick play availability, and commercial viewing management information.

(Additional remark 10) It has the non-volatile memory which stores the hash value which shows that the said content management information is the newest,
The encrypted content storage unit stores the encrypted content management information;
The content management unit compares the hash value with the content management information when using the digital content stored in the encrypted content storage unit, so that the content management information is the latest. The digital content recording apparatus according to claim 1, wherein the digital content recording apparatus is detected.

(Supplementary note 11) The digital content recording apparatus according to supplementary note 1, wherein the tamper resistant module further includes a public key encryption circuit, and performs mutual authentication with a public key management center.
(Supplementary note 12) a decryption unit for decrypting the digital content subjected to the first encryption;
An encryption unit that performs second encryption on the decrypted digital content and outputs to the content storage unit;
A content management unit that restricts use of the digital content for each type of recording medium based on content management information having information for each type of recording medium for recording the digital content stored in the content storage unit; ,
A tamper-resistant module characterized by comprising:

It is a figure which shows the structure of the digital content recording device of 1st Embodiment. It is a figure which shows the 1st example of content management information. It is a figure which shows the 2nd example of content management information. It is a figure which shows the structure of the digital content recording device of 2nd Embodiment. It is a figure which shows the structure of an example of the conventional digital television broadcast receiver.

Explanation of symbols

10 Digital Content Recording Device 11 Tuner 12 IC Card 13 Nonvolatile Memory 14 Bus 15 HDD
16 DRAM
DESCRIPTION OF SYMBOLS 17 Output circuit 17a Display apparatus 17b Speaker 18 Interface part 18-1, 18-2, ..., 18-n Recording medium 19 Processor 20 Tamper resistant module 21 Decryption circuit 22 Encryption circuit 23 Content management part 24 Software processing protection part

Claims (5)

In a digital content recording device that records digital content with copy restrictions,
A decryption unit for decrypting the digital content subjected to the first encryption;
An encryption unit for performing second encryption on the decrypted digital content;
An encrypted content storage unit for storing the digital content subjected to the second encryption;
A content management unit that restricts use of the digital content for each type of the recording medium based on content management information having information for each type of the recording medium for recording the stored digital content;
Have
A digital content recording apparatus, wherein the decryption unit, the encryption unit, and the content management unit are built in a tamper resistant module. The content management information includes information on the number of recordable times for each type of the recording medium,
2. The digital content recording apparatus according to claim 1, wherein the content management unit updates the recordable number of information every time the digital content is recorded on the recording medium. The encryption unit performs the second encryption with different encryption key information for each type of the recording medium,
The content management information includes the encryption key information that is different for each type of the recording medium,
The digital content recording apparatus according to claim 1, wherein the content management unit deletes the encryption key information corresponding to the type of the recorded recording medium.   2. The digital content recording apparatus according to claim 1, wherein a plurality of processing circuits for performing recording processing according to the type of the recording medium are further incorporated in the tamper resistant module. A decryption unit for decrypting the digital content subjected to the first encryption;
An encryption unit that performs second encryption on the decrypted digital content and outputs to the content storage unit;
A content management unit that restricts use of the digital content for each type of recording medium based on content management information having information for each type of recording medium for recording the digital content stored in the content storage unit; ,
A tamper-resistant module characterized by comprising:

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